Monday, December 31, 2012

In the period just before they went extinct, the American lions and saber-toothed cats that roamed North America in the late Pleistocene were living well off the fat of the land.

That is the conclusion of the latest study of the microscopic wear patterns on the teeth of these great cats recovered from the La Brea tar pits in southern California. Contrary to previous studies, the analysis did not find any indications that the giant carnivores were having increased trouble finding prey in the period before they went extinct 12,000 years ago.

The results, published on Dec. 26 in the scientific journal PLOS ONE, contradicts previous dental studies and presents a problem for the most popular explanations for the Megafaunal (or Quaternary) extinction when the great cats, mammoths and a number of the largest mammals that existed around the world disappeared.

"The popular theory for the Megafaunal extinction is that either the changing climate at the end of the last Ice Age or human activity – or some combination of the two – killed off most of the large mammals," said Larisa DeSantis, assistant professor of earth and environmental sciences at Vanderbilt, who headed the study. "In the case of the great cats, we expect that it would have been increasingly difficult for them to find prey, especially if had to compete with humans. We know that when food becomes scarce, carnivores like the great cats tend to consume more of the carcasses they kill. If they spent more time chomping on bones, it should cause detectable changes in the wear patterns on their teeth."

In 1993, Blaire Van Valkenburgh at UCLA published a paper on tooth breakage in large carnivores in the late Pleistocene. Analyzing teeth of American lions, saber-tooth cats, dire wolves and coyotes from La Brea, she found that they had approximately three times the number of broken teeth of contemporary predators and concluded, "...these findings suggest that these species utilized carcasses more fully and likely competed more intensely for food than present-day large carnivores."

The latest study uses a new technique, called dental microwear texture analysis (DMTA), developed by co-authorPeter Ungar at the University of Arkansas. It uses a confocal microscope to produce a three-dimensional image of the surface of a tooth. The image is then analyzed for microscopic wear patterns. Chowing down on red meat produces small parallel scratches. Chomping on bones adds larger, deeper pits. Previous methods of dental wear analysis relied on researchers to identify and count these different types of features. DMTA relies on automated software and is considered more accurate because it reduces the possibility of observer bias.

DeSantis and Ungar, with the assistance of Blaine Schubert from East Tennessee State University and Jessica Scott from the University of Arkansas, applied DMTA to the fossil teeth of 15 American lions (Panthera atrox) and 15 saber-tooth cats (Smilodon fatalis) recovered from the La Brea tar pits in Los Angeles.

Their analysis revealed that the wear pattern on the teeth of the American lion most closely resembled those of the present-day cheetah, which actively avoids bones when it feeds. Similarly, the saber-tooth cat's wear pattern most closely resembled those of the present-day African lion, which indulges in some bone crushing when it eats. (This differs from a previous microwear study using a different technique that concluded saber-tooth cats avoided bone to a far greater extent.)

The researchers examined how these patterns changed over time by selecting specimens from tar pits of different ages, ranging from about 35,000 to 11,500 years ago. They did not find any evidence that the two carnivores increased their "utilization" of carcasses throughout this period. If anything, their analysis suggests that the proportion of the carcasses that both kinds of cats consumed actually declined toward the end.

The researchers acknowledge the high rate of tooth breakage reported in the previous study, but they argue that it is more likely the result of increased breakage when taking down prey instead of when feeding.

"Teeth can break from the stress of chewing bone but they can also break when the carnivores take down prey," DeSantis pointed out. Species like hyenas that regularly chew and crack bones of their kills are as likely to break the rear teeth they use for chewing as their front canines. Species like the cheetah, however, which avoid bones during feeding are twice as likely to break canines than rear teeth. This suggests that they are more likely to break canines when pulling down prey.

The researchers report that previous examinations of the jaws of the American lions and saber-tooth cats from this period found that they have more than three times as many broken canines and interpret this as additional evidence that supports their conclusion that most of the excess tooth breakage occurred during capture instead of feeding.

In addition, the researchers argue that the large size of the extinct carnivores and their prey can help explain the large number of broken teeth. The saber-toothed cats were about the size of today's African lion and the American lion was about 25 percent larger. The animals that they preyed upon likely included mammoths, four-ton giant ground sloths and 3,500-pound bison.

The climate after the largest mass extinction so far 252 million years ago was cool, later very warm and then cool again. Thanks to the cooler temperatures, the diversity of marine fauna ballooned, as paleontologists from the University of Zurich have reconstructed. The warmer climate, coupled with a high CO2 level in the atmosphere, initially gave rise to new, short-lived species. In the longer term, however, this climate change had an adverse effect on biodiversity and caused species to become extinct.

Until now, it was always assumed that it took flora and fauna a long time to recover from the vast mass extinction at the end of the Permian geological period 252 million years ago. According to the scientific consensus, complex ecological communities only began to reappear in the Middle Triassic, so 247 million years ago. Now, however, a Swiss team headed by paleontologist Hugo Bucher from the University of Zurich reveals that marine animal groups such as ammonoids and conodonts (microfossils) already peaked three or four million years earlier, namely still during the Early Triassic.

The scientists chart the temperature curves in detail in Nature Geoscience, demonstrating that the climate and the carbon dioxide level in the atmosphere fluctuated greatly during the Early Triassic and what impact this had on marine biodiversity and terrestrial plants.

For their climate reconstruction, Bucher and his colleagues analyzed the composition of the oxygen isotopes in conodonts, the remains of chordates that once lived in the sea. According to the study, the climate at the beginning of the Triassic 249 million years ago was cool. This cooler phase was followed by a brief very warm climate phase. At the end of the Early Triassic, namely between 247.9 and 245.9 million years ago, cooler conditions resumed.

Climate and carbon cycle influence biodiversity

The scientists then examined the impact of the climate on the development of flora and fauna. “Biodiversity increased most in the cooler phases,” explains paleontologist Bucher. “The subsequent extremely warm phase, however, led to great changes in the marine fauna and a major ecological shift in the flora.” Bucher and his team can reveal that this decline in biodiversity in the warm phases correlates with strong fluctuations in the carbon isotope composition of the atmosphere. These, in turn, were directly related to carbon dioxide gases, which stemmed from volcanic eruptions in the Siberian Large Igneous Province.

Species emerge and die out

Through the climatic changes, conodont and ammonoid faunae were initially able to recover very quickly during the Early Triassic as unusually short-lived species emerged. However, the removal of excess CO2 by primary producers such as algae and terrestrial plants had adverse effects in the long run: The removal of these vast amounts of organic matter used up the majority of the oxygen in the water. Due to the lack of oxygen in the oceans, many marine species died out. “Our studies reveal that greater climatic changes can lead to both the emergence and extinction of species. Thus, it is important to consider both extinction rates and the rate at which new species emerged,” says Bucher.

Bucher and his colleagues are convinced that climate changes and the emission of volcanic gases were key drivers of biotic recovery in the oceans during the Early Triassic: Cooler climate phases encourage biological diversification. Warmer climate phases and very high CO2 levels in the atmosphere, however, can have a harmful impact on biodiversity.

Sunday, December 30, 2012

Large trees in their original living position, early flowering plants, seed cones and rare insects preserved in a rock formation were discovered by researchers in the Chatham Islands. The find reveals what is believed to be the first records of life close to the South Pole during the Cretaceous period, a time of extreme greenhouse conditions 145-65 million years ago.

Led by palaeontologist Associate Professor Jeffrey Stilwell and palaeobotanist Dr Chris Mays from Monash University's School of Geosciences, a research team including Professor David Cantrill from the Royal Botanic Gardens Melbourne made the discovery.

Associate Professor Stilwell said the fossils painted a picture of the formerly unknown life of the Cretaceous period when many southern continents including New Zealand and the Chatham Islands (Zealandia), Australia, Antarctica and South America were still mostly joined together as part of the southern landmass Gondwana.

"One hundred million years ago, the Earth was in the grip of a greenhouse effect – a planet of extreme heat with minimal ice (except in the high altitudes) and sea levels of up to 200 metres higher than today," Associate Professor Stilwell said.

"Rainforests inhabited by dinosaurs existed in sub-polar latitudes and polar ecosystems were adapted to long months of winter darkness and summer daylight.

"Never before have we had evidence about what life existed near the South Pole 90 to 100 million years, or the conditions that life on land experienced.

The discovery, 865 kilometres east of New Zealand, was made in one the most remote fossil locations known in the Southern Hemisphere while researchers were investigating a bone bed further north on Chatham Island and plant remains on nearby Pitt Island.

Friday, December 21, 2012

To incriminate a global catastrophe in the extinction of a wide swath of the biosphere, you need precise dates for two events: the catastrophe—say, an asteroid impact or volcanic eruption—and the mass extinction. At the meeting, geochronologists who measure the passage of time in the steady ticking of radioactive decay presented convincing evidence that massive eruptions at the opening of the Atlantic Ocean 201 million years ago drove the mass extinction that cleared the way for the rise of the dinosaurs.

The dating—by Terrence Blackburn of the Carnegie Institution for Science in Washington, D.C., and colleagues—was impressively precise. For minerals from the end of the Triassic period, 201 million years ago, the researchers reported ages to three decimal places with a 1-sigma error of about 30,000 years, just 0.015% of the ages. That kind of precision takes careful measurements of the amounts of the radioactive element of interest and the product of its decay. That's quite a feat in mineral grains that have been ravaged for hundreds of millions of years by both the environment and their own radioactivity.

[...]

Near the end of the Triassic period, millions of cubic kilometers of magma spewed from the crack that split the supercontinent Pangaea in two and started the opening of the Atlantic Ocean. Debris from the eruptions might have chilled the climate or poisoned the environment, triggering the extinction. But previous dating had had the extinction coming before the first volcanic outburst, not at the same time.

So Blackburn and his colleagues used the latest uranium-lead techniques to date volcanic samples from seven sites on the East coast of North America and one site in Morocco. They dated the end-Triassic extinction to 201.562±0.016 million years ago (subject to change in peer review). Adding in dating of sediments surrounding eruption deposits by using astronomical cycles, they could correlate the Moroccan record to the North American record, placing the extinction at the first of three eruption pulses within the small dating errors. And those errors have gotten so small that no one is disputing that the Atlantic opening megaeruptions somehow did in enough critters to unleash the dinosaurs.

Thursday, December 20, 2012

A growing body of scientific evidence ranks Mexico and its southern neighbors near the top of the list of countries most vulnerable to global warming, and advances in micro-forecasting foresee a grim future in alarming detail.

According to two new studies, a deadly combination of warmer weather and less rainfall in the years ahead will devastate yields of traditional crops like corn and beans, as well as the region's market-critical coffee harvest.

The ultra-local projections with shorter time horizons - as soon as the 2020s - include color-coded maps that for the first time provide virtually farm-specific climate change predictions, an innovation scientists hope will convince local stakeholders to plan accordingly.

That could mean switching to new seeds, shifting to hardier crops, or even abandoning long-established family farms.

The new research dissects the region that gave birth to modern corn and today produces a fifth of the world's high-end Arabica coffee beans, offering predictions at a level of detail of just one square kilometer, a leap in precision.

"There's a lot of potential here," said Jerry Meehl, a climate change scientist who shared in the 2007 Nobel Peace Prize won by the Intergovernmental Panel on Climate Change and former U.S. Vice President Al Gore. "What you want at the end of the day is information people can use."

According to Meehl, head of climate and global dynamics at the National Center for Atmospheric Research in Boulder, Colorado, the latest downscaled studies for agriculture in Mexico and Central America are among the highest-resolution climate change projections anywhere in the world.

The same countries are among the most threatened by climate change.

Mexico stands to lose between a quarter and a third of its agricultural production by 2080, according to a study by William Cline of the Washington, D.C.-based Center for Global Development. That is more than any country besides India.

"Now we have to focus on mitigation strategies that can make the impact we feel less painful," said Francisco Mayorga just before he left office as Mexico's agriculture minister on December 1.

Central America will see agricultural output shrink between 12 and 24 percent, according to Cline, a loss cushioned by the region's average rainfall of some 6 millimeters per day, compared with Mexico's 2 millimeters per day.

"The fundamental problem is that water needs will go up as the heat rises, but unfortunately these countries will be getting less water," said Cline.

I know of several climate scientists that are not that impressed with the regional simulations. They have repeated stated that the edges of the simulation where it couples with the larger world climate sim give less than desirable results. They have stated they really want a 500 petaflop sustained machine to get these simulations on a global scale done right. We're still at 1/30th the processing power to do that looking at the latest Top 500.

Mosasauroids are conventionally conceived of as gigantic, obligatorily aquatic marine lizards (1000s of specimens from marine deposited rocks) with a cosmopolitan distribution in the Late Cretaceous (90–65 million years ago [mya]) oceans and seas of the world. Here we report on the fossilized remains of numerous individuals (small juveniles to large adults) of a new taxon, Pannoniasaurus inexpectatus gen. et sp. nov. from the Csehbánya Formation, Hungary (Santonian, Upper Cretaceous, 85.3–83.5 mya) that represent the first known mosasauroid that lived in freshwater environments. Previous to this find, only one specimen of a marine mosasauroid, cf. Plioplatecarpus sp., is known from non-marine rocks in Western Canada. Pannoniasaurus inexpectatus gen. et sp. nov. uniquely possesses a plesiomorphic pelvic anatomy, a non-mosasauroid but pontosaur-like tail osteology, possibly limbs like a terrestrial lizard, and a flattened, crocodile-like skull. Cladistic analysis reconstructs P. inexpectatus in a new clade of mosasauroids: (Pannoniasaurus (Tethysaurus (Yaguarasaurus, Russellosaurus))). P. inexpectatus is part of a mixed terrestrial and freshwater faunal assemblage that includes fishes, amphibians turtles, terrestrial lizards, crocodiles, pterosaurs, dinosaurs and birds.

Note: one of the things I've seen is that Pannoniasaurus is reconstructed with terrestrial style legs. THe authors caution that the legs aren't really known.

a. School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin, Ireland

b. School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom

Abstract:

The distribution of species body size is critically important for determining resource use within a group or clade. It is widely known that non-avian dinosaurs were the largest creatures to roam the Earth. There is, however, little understanding of how maximum species body size was distributed among the dinosaurs. Do they share a similar distribution to modern day vertebrate groups in spite of their large size, or did they exhibit fundamentally different distributions due to unique evolutionary pressures and adaptations? Here, we address this question by comparing the distribution of maximum species body size for dinosaurs to an extensive set of extant and extinct vertebrate groups. We also examine the body size distribution of dinosaurs by various sub-groups, time periods and formations. We find that dinosaurs exhibit a strong skew towards larger species, in direct contrast to modern day vertebrates. This pattern is not solely an artefact of bias in the fossil record, as demonstrated by contrasting distributions in two major extinct groups and supports the hypothesis that dinosaurs exhibited a fundamentally different life history strategy to other terrestrial vertebrates. A disparity in the size distribution of the herbivorous Ornithischia and Sauropodomorpha and the largely carnivorous Theropoda suggests that this pattern may have been a product of a divergence in evolutionary strategies: herbivorous dinosaurs rapidly evolved large size to escape predation by carnivores and maximise digestive efficiency; carnivores had sufficient resources among juvenile dinosaurs and non-dinosaurian prey to achieve optimal success at smaller body size.

Wednesday, December 19, 2012

A new mosasaur species discovered in Hungary is the first known example of this group of scaled reptiles to have lived in freshwater river environments similar to modern freshwater dolphins, according to research published December 19 in the open-access journal PLOS ONE by Laszlo Makadi from the Hungarian Natural History Museum, Hungary and colleagues from the University of Alberta, Canada and MTA-ELTE Lendület Dinosaur Research Group, Hungary.

The species lived about 84 million years ago, the largest specimens reached about 20 feet in length, and belongs to a family called ‘mosasaurs’, conventionally thought of as gigantic finned marine lizards, similar and perhaps even related to present day monitor lizards. The researchers discovered several fossils of the new species, ranging from small juveniles to large adults that suggest that this species had limbs like a terrestrial lizard, a flattened, crocodile-like skull, and a tail unlike other known members of the mosasaur family.

The fossils were recovered from an open-pit mine in the Bakony Hills of Western Hungary, which were once flood-plains. According to the study, this is the first known mosasaur that lived in freshwater, and only the second specimen of a mosasaur to have been found in rocks that were not once deposited in the ocean. Makadi says, "The evidence we provide here makes it clear that similar to some lineages of cetaceans, mosasaurs quickly adapted to a variety of aquatic environments, with some groups re- invading available niches in freshwater habitats. The size of Pannoniasaurus makes it the largest known predator in the waters of this paleo-environment."

Update: This is probably a hoax. The reason that I thought /maybe/ it was not was that eagles are noted for attacking many things larger than themselves. Darren Naish has an article about just that. Though it may be on the science blogs version of Tetrapod Zoology.

Synchrotron-based imaging techniques of a 50 million-year-old lizard skin have identified the presence of teeth which are invisible to visible light, demonstrating for the first time that this fossil animal was more than just a skin moult.

Researchers used Synchrotron Rapid Screening X-ray Fluorescence at the Stanford Synchrotron Radiation Lightsource in California to map the chemical make up of a rare fossil lizard skin - powerful x-rays enabled the team to map the presence of phosphorus from teeth in this ancient reptile.

The relative position of the phosphorous in the skin fossil helped the scientists identify the type of lizard. They believe that the more elongated snout in conjunction with the general jaw shape bears a strong resemblance to a shinisaurid lizard (Bahndwivici ammoskius). The presence of phosphorous also demonstrates for the first time that the fossil skin is more than just a moult, as no lizards can shed their teeth along with their skin!

Dr. Phil Manning from the Palaeontology Research group at the University of Manchester said, "Finding the presence of teeth changes almost everything we thought we knew about this fossil. We can identify the type of lizard for the first time, based upon the geometry of the teeth. Our findings also raise some fascinating questions about what happened to the animal after its death. What wiped out its bones but preserved the skin and the ghost of its teeth?

"The technique permits us to tease-out chemical information from fossils, information that you simply cannot see with the naked eye. Such chemical maps can help us see 'ghosts' of original biological structures that only remain in very dilute concentrations in the fossil."

Tuesday, December 18, 2012

Cheap shale gas is significantly reducing coal demand in the United States, but global coal consumption is still expected to rise 2.6 percent annually by 2017, the International Energy Agency said today in a report.

Coal consumption will climb to 4.32 billion tons of oil equivalent by 2017, nearly matching oil consumption of about 4.4 billion, the Paris-based agency said in its first Medium-Term Coal Market Report.

"Coal's share of the global energy mix continues to grow each year, and if no changes are made to current policies, coal will catch oil within a decade," said Maria van der Hoeven, IEA's executive director.

Demand for coal rose 4.3 percent last year, with China accounting for 67 percent of the increase and replacing Japan as the largest importer, the report says. Coal demand and carbon dioxide emissions from coal will continue to increase unless climate change policies are introduced, the IEA said.

Countries outside the Organisation for Economic Co-operation and Development are expected to drive growth with an annual increase of 3.9 percent. Within the OECD, coal use will drop by 0.7 percent a year, led by a 2.5 percent drop in U.S. demand per year to 600 million metric tons in 2017, the IEA said.

"Coal demand never stropped growing in the financial crisis and despite aggressive climate policies in many places," van der Hoeven said in a teleconference with journalists. "The only significant decline in coal consumption globally was in the United States, and the reason is cheap gas."

Total world consumption of coal will be 6.17 billion tons in 2017, up from 5.28 billion last year, the report forecasts.

"The impact of the coal-to-gas switch in North America is so significant that for the first time since China's rise, the medium-term growth rate in coal consumption will fall below the growth rate of gas," van der Hoeven said.

The world will burn around 1.2 billion more tons of coal per year by 2017 compared to today, equivalent to the current coal consumption of Russia and the United States combined. China will account for 70 percent of the growth in coal demand over the next five years, while India will make up 22 percent, the report says.

"India becomes the second-largest coal consumer and the largest coal importer in the world," van der Hoeven said. "Together, by 2017, China and India represent more than one-third of global coal imports and two-thirds of global coal demand. It's clear that the Chinese and Indian coal market decisions will have an impact on our electricity bills."

India's coal demand will increase by 6.3 percent per year to 643 million tons by 2017, IEA said. Australia will become the world's largest coal exporter by 2017, shipping 356 million tons of coal equivalent, the report says.

There are times when I wish I was wrong...but I predicted this stuff almost six years ago. The exception is that I did not see the US demand for coal sliding because of natural gas. However, as I point out in my post, it won't matter if the US or Europe drop their carbon output...China and India will more than make up for it. And since neither of those countries are willing to bind themselves and say that the West (ahem, developed countries) must bear the burden of CO2 reduction.

The amount of land needed to grow crops worldwide is at a peak, and a geographical area more than twice the size of France will be able to return to its natural state by 2060 as a result of rising yields and slower population growth, a group of experts said on Monday.

Their report, conflicting with United Nations studies that say more cropland will be needed in coming decades to avert hunger and price spikes as the world population rises above 7 billion, said humanity had reached what it called "Peak Farmland".

More crops for use as biofuels and increased meat consumption in emerging economies such as China and India, demanding more cropland to feed livestock, would not offset a fall from the peak driven by improved yields, it calculated.

If the report is accurate, the land freed up from crop farming would be some 10 percent of what is currently in use - equivalent to 2.5 times the size of France, Europe's biggest country bar Russia, or more than all the arable land now utilized in China.

"We believe that humanity has reached Peak Farmland, and that a large net global restoration of land to nature is ready to begin," said Jesse Ausubel, director of the Program for the Human Environment at the Rockefeller University in New York.

"Happily, the cause is not exhaustion of arable land, as many had feared, but rather moderation of population and tastes and ingenuity of farmers," he wrote in a speech about the study he led in the journal Population and Development Review.

Nearly all data regarding land-plant turnover across the Cretaceous/Paleogene boundary come from western North America, relatively close to the Chicxulub, Mexico impact site. Here, we present a palynological analysis of a section in Patagonia that shows a marked fall in diversity and abundance of nearly all plant groups across the K/Pg interval. Minimum diversity occurs during the earliest Danian, but only a few palynomorphs show true extinctions. The low extinction rate is similar to previous observations from New Zealand. The differing responses between the Southern and Northern hemispheres could be related to the attenuation of damage with increased distance from the impact site, to hemispheric differences in extinction severity, or to both effects. Legacy effects of the terminal Cretaceous event also provide a plausible, partial explanation for the fact that Paleocene and Eocene macrofloras from Patagonia are among the most diverse known globally. Also of great interest, earliest Danian assemblages are dominated by the gymnosperm palynomorphs Classopollis of the extinct Mesozoic conifer family Cheirolepidiaceae. The expansion of Classopollis after the boundary in Patagonia is another example of typically Mesozoic plant lineages surviving into the Cenozoic in southern Gondwanan areas, and this greatly supports previous hypotheses of high latitude southern regions as biodiversity refugia during the end-Cretaceous global crisis.

Gliese 667 is a triple star system about 22 light years from Earth in the constellation of Scorpius. Two of these stars–Gliese 667 A and B–are Sun-like and orbit each other relatively closely.

The third is much more interesting. Gliese 667C a red dwarf that is about a third of the mass of our Sun and only about 1 per cent as bright. It orbits the other two stars at a much greater distance: some 200 astronomical units or about 30 billion kilometres.

Red dwarfs are particularly interesting for astronomers because their small mass makes it much easier to spot orbiting planets. What’s more, their low luminosity means that these stars’ habitable zones are much closer than for brighter stars.

Since current planet spotting techniques favour closer planets, astronomers know they are much more likely to find planets in the habitable zone around red dwarfs. In fact, today’s news is a good example.

Today, Philip Gregory at the University of British Columbia in Canada says that Gliese 667Chas three planets sitting squarely in the middle of its habitable zone.

Gregory is a pioneer of new statistical techniques for evaluating the data from planet-hunting instruments. “The excitement generated by … many … exoplanetary discoveries has spurred a signiﬁcant eﬀort to improve the statistical tools for analyzing data in this ﬁeld,” he says.

So he’s used a new technique to re-examine data on Gliese 667C taken by the High Accuracy Radial velocity Planet Searcher, HARPS, attached the European Southern Observatory’s 3.6 metre telescope in Chile.

He says this analysis indicates that the most likely number of planets around Gliese 667C is 6 with orbital periods of 7 days, 28 days, 31 days, 39 days, 53 days and 91 days. Only two of these were already known.

However, the most interesting news is that the 28, 31 and 39 day-planets are all smack bang in the middle of the habitable zone, he says.

These planets are all larger than Earth but the 39 day period planet (planet e) is only just over twice Earth’s mass. That makes it “the lowest mass planet in the habitable zone detected to date,” says Gregory.

Keep in mind that Mars is in the habitable zone and yet does not seem to be biologically active. Likewise, Venus is on inner edge of the habitable zone and...zip.

Even so, the prospect of multiple planets in a single system having planets is awesome.

Monday, December 17, 2012

Scientists have found a new culprit in spreading the disease that's been driving the world's frogs to the brink of extinction: crayfish.

In the last few decades, the disease caused by the chytrid fungus has been a disaster for frogs and other amphibians. More than 300 species are nearly extinct because of it. Many probably have gone extinct, but it can be difficult to know for sure when a tiny, rare species disappears from the face of the Earth.

"This pathogen is bad news. It's worse news than any other pathogen in the history of life on Earth as far as we know it," says Vance Vredenburg, a conservation biologist at San Francisco State University who studies frogs but did not work on the new study.

The chytrid fungus was only discovered in the late 1990s. Since then, scientists have been scrambling to figure out how it spreads and how it works.

One of the biggest mysteries is how chytrid can persist in a frogless pond. Researchers saw it happen many times and were perplexed: If all of a pond's amphibians were wiped out, and a few frogs or salamanders came back and recolonized the pond, they would also die—even though there were no amphibians in the pond to harbor the disease.

One possible reason is that chytrid infects other animals. For a study published today in Proceedings of the National Academy of Sciences, Taegan McMahon, a graduate student in ecology at the University of South Florida in Tampa, looked at some possible suspects and focused on crayfish, those lobsterlike crustaceans living in freshwater. They seemed like a good possibility because they're widespread and because their bodies have a lot of keratin, a protein the fungus attacks.

In the lab, McMahon exposed crayfish to the disease and they got sick. More than a third died within seven weeks, and most of the survivors were carrying the fungus. She also put infected crayfish in the water with tadpoles—separated by mesh, so the crustaceans wouldn't eat the baby frogs—and the tadpoles got infected. When McMahon and her colleagues checked out wetlands in Louisiana and Colorado, they also found infected crayfish.

That means crayfish can probably act as a reservoir for the disease. The fungus seems to be able to dine on crayfish then leap back to amphibians when it gets a chance. No one knows for sure where the fungus originally came from or why it's been such a problem in recent decades, but this research suggests one way that it could have been spread. Crayfish are sometimes moved from pond to pond as fish bait and are sold around the world as food and aquarium pets.

Friday, December 14, 2012

Jamming radar signals is an increasingly sophisticated affair. There are various techniques such as drowning the radar frequency with noise or dropping chaff to create a false reflection. But the most advanced radar systems can get around these ruses.

So a more sophisticated idea is to intercept the radar signal and modify it in a way that gives false information about the target before sending it back. That’s much harder to outsmart.

But today, Mehul Malik and pals at the University of Rochester in New York state demonstrate a way to do it.

These guys base their technique on the quantum properties of photons and in particular on the fact that any attempt to measure a photon always destroys its quantum properties.

So their idea is to use polarized photons to detect and image objects. Reflected photons can of course be used to build up an image of the object. But an adversary could intercept these photons and resend them in a way that disguises the object’s shape or makes it look as if it is elsewhere.

However, such a process would always change the quantum properties of the photons such as their polarization. And so it should always be possible to detect such interference. “In order to jam our imaging system, the object must disturb the delicate quantum state of the imaging photons, thus introducing statistical errors that reveal its activity,” say Malik and co.

That’s more or less exactly how quantum key distribution for cryptography works. The idea here is that any eavesdropper would change the quantum properties of the key and so reveal his or her presence. The only difference in the quantum imaging scenario is that the “message” is sent and received by the same person.

Malik and co have tested their idea by bouncing photons off an aeroplane-shaped target and measuring the polarization error rate in the return signal. Without any eavesdropping the system easily imaged the aeroplane.

But when an adversary intercepted the photons and modified them to send back an image of a bird, the interference was easy to spot, say Malik and co.

That’s an impressive demonstration of the first imaging system that is unjammable thanks to quantum mechanics.

New genetic analysis has revealed that many Amazon tree species are likely to survive man-made climate warming in the coming century, contrary to previous findings that temperature increases would cause them to die out.

A study, published in the latest edition of Ecology and Evolution, reveals the surprising age of some Amazonian tree species – more than 8 million years – and therefore shows that they have survived previous periods as warm as many of the global warming scenarios forecast for the year 2100.

The authors write that, having survived warm periods in the past, the trees will likely survive future warming, provided there are no other major environmental changes. Although extreme droughts and forest fires will impact Amazonia as temperatures rise, the trees will likely endure the direct impact of higher temperatures. The authors recommend that as well as reducing greenhouse gas emissions to minimise the risk of drought and fire, conservation policy should remain focused on preventing deforestation for agriculture and mining.

The study is at odds with other recent research, based on ecological niche-modeling scenarios, which predicted tree species' extinctions in response to relatively small increases in global average air temperatures.

Study co-author Dr Simon Lewis (UCL Geography) said the findings were good news for Amazon tree species, but warned that drought and over-exploitation of the forest remained major threats to the Amazon's future.

Dr Lewis said: "The past cannot be compared directly with the future. While tree species seem likely to tolerate higher air temperatures than today, the Amazon forest is being converted for agriculture and mining, and what remains is being degraded by logging, and increasingly fragmented by fields and roads.

"Species will not move as freely in today's Amazon as they did in previous warm periods, when there was no human influence. Similarly, today's climate change is extremely fast, making comparisons with slower changes in the past difficult.

"With a clearer understanding of the relative risks to the Amazon forest, we conclude that direct human impacts – such as forest clearances for agriculture or mining – should remain a focus of conservation policy. We also need more aggressive action to reduce greenhouse gas emissions in order to minimise the risk of drought and fire impacts to secure the future of most Amazon tree species."

The 12 tree species used in the study are broadly representative of the Amazon tree flora. Samples were collected in Panama, Ecuador, Brazil, Peru, French Guiana and Bolivia.

To determine the age of each tree species researchers extracted and sequenced DNA, analysing the number of genetic mutations. Using a molecular clock approach and population genetic models they estimated how long it would take for each of the species to accumulate the observed number of mutations, providing a minimum age for each species. They determined that nine of the tree species had existed for at least 2.6 million years, seven for at least 5.6 million years, and three for more than 8 million years.

Thursday, December 13, 2012

[Bustamante's] lab has entered the field of synthetic biology and is working towards creating a living organism by furnishing mitochondria with the genes that might make them independent from their host cells. Mitochondria are energy-generating organelles that are found inside the cells of all eukaryotic organisms such as plants, animals, and humans. They are thought to be descendants of a bacterium that was engulfed by another cell at some point during the evolution of life. Since then, mitochondria have lost most of their genes and cannot live independently anymore, but rely on their host cell for survival. Research in the Bustamante lab aims at reintroducing the essential genes into mitochondria that will make them independent once again, to gain a better understanding of the minimal set of genes that constitutes life.

The link is more a profile of Dr Bustamante than about his research. However, I couldn't resist the idea of Berkeley espousing freedom for mitochondria! Synthetic Biology Shall Set You Free!!!

Wednesday, December 12, 2012

Ancient multicellular fossils long thought to be ancestors of early marine life are remnants of land-dwelling lichen or other microbial colonies, says University of Oregon scientist Gregory Retallack, who has been studying fossil soils of South Australia.

Ediacaran (pronounced EDI-akran) fossils date to 542-635 million years ago. They've been considered fossil jellyfish, worms and sea pens, but are preserved in ways distinct from marine invertebrate fossils. The fossils -- first discovered in 1946 in Australia's Ediacara Hills -- are found in iron-colored impressions similar to plant fossils and microbes in fossil soils.

Retallack, a native of Australia, examined ancient Ediacaran soils with an array of state-of-the-art chemical and microscopic techniques, including an electron microprobe and scanning electron microscope in the UO's CAMCOR Microanalytical Facility headed by John Donovan and rock-analysis technology in the UO's stable isotope laboratory of Ilya Bindeman.

The soils with fossils, Retallack writes in his study, "are distinguished by a surface called 'old elephant skin,' which is best preserved under covering sandstone beds." The healed cracks and lumpy appearance of sandy "old elephant skin" are most like the surface of microbial soil crusts in modern deserts.

"This discovery has implications for the tree of life, because it removes Ediacaran fossils from the ancestry of animals," said Retallack, professor of geological sciences and co-director of paleontological collections at the UO's Museum of Natural and Cultural History. His evidence, mostly gathered from a site in the Flinders Ranges, is presented in a paper placed online ahead of print by the journal Nature.

"These fossils have been a first-class scientific mystery," he said. "They are the oldest large multicellular fossils. They lived immediately before the Cambrian evolutionary explosion that gave rise to familiar modern groups of animals."

Retallack studied numerous Ediacaran fossils and determined that the diversity reflects a preference by the ancient organisms for "unfrozen, low salinity soils, rich in nutrients, like most terrestrial organisms." Thus the fossils in Australia's iconic red-rock ranges, he concludes, were landlubbers. In his closing paragraph, Retallack outlines implications for a variety of other Edicaran fossils, that could have been lichens, other microbial consortia, fungal fruiting bodies, slime molds, flanged pedestals of biological soil crusts, and even casts of needle ice.

Ediacaran fossils, he said, represent "an independent evolutionary radiation of life on land that preceded by at least 20 million years the Cambrian evolutionary explosion of animals in the sea." Increased chemical weathering by large organisms on land may have been needed to fuel the demand of nutrient elements by Cambrian animals. Independent discoveries of Cambrian fossils comparable with Ediacaran ones is evidence, he said, that even in the Cambrian, more than 500 million years ago, life on land may have been larger and more complex than life in the sea.

Retallack leaves open the possibility that some Ediacaran fossils found elsewhere in the world may not be land-based in origin, writing in his conclusion that the many different kinds of these fossils need to be tested and re-evaluated.

I think this one counts as ... out there. I'd love to see the firestorm this releases!

Tuesday, December 11, 2012

'It is exciting to discover that a common group of fossils that we thought we knew a lot about may well have been hood-winking us as to their true identity, which we now realise because we have their beautifully fossilised soft-parts. A case of a 'wolf in sheep's clothing''- Professor David Siveter, University of Leicester

An international team of researchers have made an extremely rare discovery of a species of animal - related to crabs, lobsters and shrimps – that is new to science.

Scientists from the universities of Leicester, Oxford, Imperial and Yale have announced their discovery of a new and scientifically important fossil species of ostracod in the journal, Proceedings of The Royal Society B. The research was funded by the Natural Environment Research Council.

The discovered species, which is up to 10 millimetres long, is special because it is exceptionally well preserved, complete with not only the shell but also the soft parts – its body, limbs, eyes, gills and alimentary system. Such discoveries are extremely rare in the fossil record.

The discovery of the tiny shelled arthropod was made in 425 million year old rocks in Herefordshire, Welsh Borderland. The rocks at the site date to the Silurian period of geological time, when southern Britain was a sea area on a small continent situated in warm, southerly subtropical latitudes. The ostracods and associated marine animals living there were covered by a fall of volcanic ash that preserved them frozen in time.

Professor David Siveter, of the University of Leicester Department of Geology, said: "The two ostracod specimens discovered represent a genus and species new to science, named Pauline avibella. The genus is named in honour of a special person and avibella means 'beautiful bird', so-named because of the fancied resemblance of a prominent feature of the shell to the wing of a bird."

"Ostracods are the most abundant fossil arthropods, occurring ubiquitously as bivalved shells in rocks of the last 490 million years, and are common in most water environments today. The find is important because it is one of only a handful preserving the fossilised soft-tissues of ostracods. Its assignment to a particular group of ostracods based on knowledge of its biology is at odds with its shell form, thus urging caution in interpreting the classification of fossil ostracods based on shell characters alone."

"The preservation of soft-parts of animals is a very rare occurrence in the fossil record and allows unparalleled insight into the ancient biology, community structure and evolution of animals - key facts that that would otherwise be lost to science. The fossils known from the Herefordshire site show soft-part preservation and are of global importance."

The fossils were reconstructed 'virtually', by using a technique that involves grinding each specimen down, layer by layer, and photographing it at each stage. Ten millimetres is relatively tiny, but at an incremental level of 20 µm (micrometres) that yields 500 slices, which can then be pieced together in a computer to provide a full, three-dimensional image of each fossil, outside and in.

The Late Pleistocene global extinction of many terrestrial mammal species has been a subject of intensive scientific study for over a century, yet the relative contributions of environmental changes and the global expansion of humans remain unresolved. A defining component of these extinctions is a bias toward large species, with the majority of small-mammal taxa apparently surviving into the present. Here, we investigate the population-level history of a key tundra-specialist small mammal, the collared lemming (Dicrostonyx torquatus), to explore whether events during the Late Pleistocene had a discernible effect beyond the large mammal fauna. Using ancient DNA techniques to sample across three sites in North-West Europe, we observe a dramatic reduction in genetic diversity in this species over the last 50,000 y. We further identify a series of extinction-recolonization events, indicating a previously unrecognized instability in Late Pleistocene small-mammal populations, which we link with climatic fluctuations. Our results reveal climate-associated, repeated regional extinctions in a keystone prey species across the Late Pleistocene, a pattern likely to have had an impact on the wider steppe-tundra community, and one that is concordant with environmental change as a major force in structuring Late Pleistocene biodiversity.

*. To whom correspondence may be addressed. E-mail: andrew.leslie@yale.edu or michael.donoghue@yale.edu.

Abstract:

Fundamental differences in the distribution of oceans and landmasses in the Northern and Southern Hemispheres potentially impact patterns of biological diversity in the two areas. The evolutionary history of conifers provides an opportunity to explore these dynamics, because the majority of extant conifer species belong to lineages that have been broadly confined to the Northern or Southern Hemisphere during the Cenozoic. Incorporating genetic information with a critical review of fossil evidence, we developed an age-calibrated phylogeny sampling ∼80% of living conifer species. Most extant conifer species diverged recently during the Neogene within clades that generally were established during the later Mesozoic, but lineages that diversified mainly in the Southern Hemisphere show a significantly older distribution of divergence ages than their counterparts in the Northern Hemisphere. Our tree topology and divergence times also are best fit by diversification models in which Northern Hemisphere conifer lineages have higher rates of species turnover than Southern Hemisphere lineages. The abundance of recent divergences in northern clades may reflect complex patterns of migration and range shifts during climatic cycles over the later Neogene leading to elevated rates of speciation and extinction, whereas the scattered persistence of mild, wetter habitats in the Southern Hemisphere may have favored the survival of older lineages.

The asteroid collision widely thought to have killed the dinosaurs also led to extreme devastation among snake and lizard species, according to new research — including the extinction of a newly identified lizard species Yale and Harvard scientists have named Obamadon gracilis.

"The asteroid event is typically thought of as affecting the dinosaurs primarily," said Nicholas R. Longrich, a postdoctoral associate with Yale's Department of Geology and Geophysics and lead author of the study. "But it basically cut this broad swath across the entire ecosystem, taking out everything. Snakes and lizards were hit extremely hard."

The study was scheduled for online publication the week of Dec. 10 in the Proceedings of the National Academy of Sciences.

Earlier studies have suggested that some snake and lizard species (as well as many mammals, birds, insects and plants) became extinct after the asteroid struck the earth 65.5 million years ago, on the edge of the Yucatan Peninsula. But the new research argues that the collision's consequences were far more serious for snakes and lizards than previously understood. As many as 83 percent of all snake and lizard species died off, the researchers said — and the bigger the creature, the more likely it was to become extinct, with no species larger than one pound surviving.

The results are based on a detailed examination of previously collected snake and lizard fossils covering a territory in western North America stretching from New Mexico in the southwestern United States to Alberta, Canada. The authors examined 21 previously known species and also identified nine new lizards and snakes.

They found that a remarkable range of reptile species lived in the last days of the dinosaurs. Some were tiny lizards. One snake was the size of a boa constrictor, large enough to take the eggs and young of many dinosaur species. Iguana-like plant-eating lizards inhabited the southwest, while carnivorous lizards hunted through the swamps and flood plains of what is now Montana, some of them up to six feet long.

"Lizards and snakes rivaled the dinosaurs in terms of diversity, making it just as much an 'Age of Lizards' as an 'Age of Dinosaurs,'" Longrich said.

The scientists then conducted a detailed analysis of the relationships of these reptiles, showing that many represented archaic lizard and snake families that disappeared at the end of the Cretaceous, following the asteroid strike.

One of the most diverse lizard branches wiped out was the Polyglyphanodontia. This broad category of lizards included up to 40 percent of all lizards then living in North America, according to the researchers. In reassessing previously collected fossils, they came across an unnamed species and called it Obamadon gracilis. In Latin, odon means "tooth" and gracilis means "slender."

"It is a small polyglyphanodontian distinguished by tall, slender teeth with large central cusps separated from small accessory cusps by lingual grooves," the researchers write of Obamadon, which is known primarily from the jaw bones of two specimens. Longrich said the creature likely measured less than one foot long and probably ate insects.

An analysis of sulfide ore deposits from one of the world's richest base-metal mines confirms that oxygen levels were extremely low on Earth 2.7 billion years ago, but also shows that microbes were actively feeding on sulfate in the ocean and influencing seawater chemistry during that geological time period.

The research, reported by a team of Canadian and U.S. scientists in Nature Geoscience, provides new insight into how ancient metal-ore deposits can be used to better understand the chemistry of the ancient oceans – and the early evolution of life.

Sulfate is the second most abundant dissolved ion in the oceans today. It comes from the "rusting" of rocks by atmospheric oxygen, which creates sulfate through chemical reactions with pyrite, the iron sulfide material known as "fool's gold."

The researchers, led by PhD student John Jamieson of the University of Ottawa and Prof. Boswell Wing of McGill, measured the "weight" of sulfur in samples of massive sulfide ore from the Kidd Creek copper-zinc mine in Timmins, Ontario, using a highly sensitive instrument known as a mass spectrometer. The weight is determined by the different amounts of isotopes of sulfur in a sample, and the abundance of different isotopes indicates how much seawater sulfate was incorporated into the massive sulfide ore that formed at the bottom of ancient oceans. That ancient ore is now found on the Earth's surface, and is particularly common in the Canadian shield.

The scientists found that much less sulfate was incorporated into the 2.7 billion-year-old ore at Kidd Creek than is incorporated into similar ore forming at the bottom of oceans today. From these measurements, the researchers were able to model how much sulfate must have been present in the ancient seawater. Their conclusion: sulfate levels were about 350 times lower than in today's ocean. Though they were extremely low, sulfate levels in the ancient ocean still supported an active global population of microbes that use sulfate to gain energy from organic carbon.

"The sulfide ore deposits that we looked at are widespread on Earth, with Canada and Quebec holding the majority of them," says Wing, an associate professor in McGill's Department of Earth and Planetary Science. "We now have a tool for probing when and where these microbes actually came into global prominence."

Saturday, December 08, 2012

Nickel-eating bacteria may have worsened the world's worst mass die-off by producing huge amounts of methane, a new study suggests.

The study is the latest attempt to explain how most of the world's ocean species died off in just a few hundred thousand years at the end of the Permian era, about 250 million years ago. The researchers presented their findings Tuesday (Dec. 4) here at the annual meeting of the American Geophysical Union.

The study proposes that a series of steps caused the mass extinction, but that bacteria played a key role. First, massive volcanic activity in Siberia released nickel into the atmosphere, which somehow reached the ocean. As a result, populations of ocean-dwelling bacteria that use nickel in their metabolic pathway exploded, releasing huge amounts of methane into the atmosphere and depleting ocean oxygen levels as a byproduct of that metabolism. Because methane is a greenhouse gas, the catastrophic gas release trapped heat in the atmosphere and caused the mass extinction by making the climate uninhabitable.

Metatherian mammals were the most diverse mammalian clade in North America through the Late Cretaceous, but they underwent a severe extinction at the Cretaceous–Palaeogene (K-Pg) boundary. In order to clarify the origin of Palaeogene metatherians and the pattern of metatherian survivorship across the K-Pg boundary we conducted an inclusive species level phylogenetic analysis of Cretaceous and early Palaeogene metatherian taxa. This analysis includes information fro new Palaeocene specimens from south-western North America. Both the phylogenetic topology and information from new specimens support the validity of the genus Thylacodon and justify the recognition of a new species, T. montanensis. Thylacodon is closely related to Swaindelphys and Herpetotheriidae, which must have diverged by the latest Cretaceous due to its close relationship with late Campanian Ectocentrocristus. Pediomyidae and ‘Peradectidae sensu lato’ together comprise a major metatherian clade. Maastrichtidelphys, from the Late Cretaceous of the Netherlands, is the oldest member of ‘Peradectidae sensu lato’, indicating a Cretaceous origination for this group. Therefore, the major groups Herpetotheriidae and ‘Peradectidae sensu lato’, represented almost completely by Palaeocene taxa, must have originated in the Late Cretaceous. The lineages leading to these clades include at least four lineages that must have crossed the K-Pg boundary and therefore confirm that the K-Pg boundary marked a profound extinction event for metatherians and suggests that Palaeogene taxa originated from only a few clades of Cretaceous species, all of which were relatively minor or very rare components of known Cretaceous mammalian faunas.

The only surviving metatherians are the marsupials. However, not all metatherians were marsupials, fyi.

The taxonomy and paleobiology of the Upper Permian dicynodont Cistecephalus have been much debated over the last century. Fossils of Cistecephalus have been identified as belonging either to one species or up to six species and hypotheses concerning their lifestyle range from aquatic to arboreal and fossorial. Earlier studies of Cistecephalus focused mainly on macroanatomical characteristics, whereas the current assessment examines a combination of anatomical features, as well as bone histology and microanatomy to unravel its biology. The allometries of a skull growth series that were examined in the present study imply that all Cistecephalus specimens belong to a single species. Furthermore, our data suggest that the variability in the occurrence of supraorbital ridges, which are raised in some specimens and leveled in others, is a feature of sexual dimorphism. Histological thin-sections of a humerus, an ulna, a femur, and ribs from two Cistecephalus specimens were studied to evaluate life history traits of this taxon. The comparison of ribs from a subadult and a fully grown specimen allows an estimation that sexual maturity was attained when the skull length was between 5.9 and 6.5 cm. The compact microstructure of the sampled Cistecephalus bones implies aquatic and/or fossorial adaptations, refuting an arboreal lifestyle. We propose that the high degree of binocular vision evident in Cistecephalus developed in response to predatory (insectivory) and/or nocturnal habits and that it is unrelated to a scansorial lifestyle.

Potentially omnivorous and fossorial. Weird, awesome little thing.

I meant to post this before and forgot...too many things going on. Good and bad.

Fossils of a two-metre tall penguin that lived in Antarctica 34 million years ago have been discovered by Argentine palaeontologists.

Palaeontologists with the Natural Sciences Museum of La Plata province, where the capital Buenos Aires is located, said the remains were found on the icy southern continent.

"This is the largest penguin known to date in terms of height and body mass," said researcher Carolina Acosta, who noted that the record had been held by emperor penguins, which reach heights of 1.2 metres tall.

a. School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia,

b. Department of Earth and Environmental Sciences, University of Adelaide, Adelaide, South Australia, Australia

Abstract:

The marsupial family Diprotodontidae (Diprotodontia, Vombatiformes) is a group of extinct large-bodied (60–2500 kg) wombat-like herbivores that were common and geographically widespread in Cenozoic fossil deposits of Australia and New Guinea. Typically they are regarded to be gregarious, terrestrial quadrupeds and have been likened in body form among placental groups to sheep, rhinoceros and hippopotami. Arguably, one of the best represented species is the zygomaturine diprotodontid Nimbadon lavarackorum which is known from exceptionally well-preserved cranial and postcranial material from the middle Miocene cave deposit AL90, in the Riversleigh World Heritage Area, northwestern Queensland. Here we describe and functionally analyse the appendicular skeleton of Nimbadon lavarackorum and reveal a far more unique lifestyle for this plesiomorphic and smallest of diprotodontids. Striking similarities are evident between the skeleton of Nimbadon and that of the extant arboreal koala Phascolarctos cinereus, including the powerfully built forelimbs, highly mobile shoulder and elbow joints, proportionately large manus and pes (both with a semi-opposable digit I) and exceedingly large, recurved and laterally compressed claws. Combined with the unique (among australidelphians) proportionately shortened hindlimbs of Nimbadon, these features suggest adept climbing ability, probable suspensory behaviour, and an arboreal lifestyle. At approximately 70 kg, Nimbadon is the largest herbivorous mammal to have occupied the forest canopies of Australia - an ecological niche that is no longer occupied in any Australian ecosystem and one that further expands the already significant niche diversity displayed by marsupials during the Cenozoic.

An international research team led by the Planetary Science Institute has found evidence that indicates that approximately 2 billion years ago enormous volumes of catastrophic floods discharges may have been captured by extensive systems of caverns on Mars, said PSI Research Scientist, J. Alexis Palmero Rodriguez.

Rodriguez and the research team came to this conclusion after studying the terminal regions of the Hebrus Valles, an outflow channel that extends approximately 250 kilometers downstream from two zones of surface collapse.

The Martian outflow channels comprise some of the largest known channels in the solar system. Although it has been proposed their discharge history may have once led to the formation of oceans, the ultimate fate and nature of the fluid discharges has remained a mystery for more than 40 years, and their excavation has been attributed to surface erosion by glaciers, debris flows, catastrophic floodwaters, and perhaps even lava flows, Rodriguez said.

The PSI-led team's work documents the geomorphology of Hebrus Valles, a Martian terrain that is unique in that it preserves pristine landforms located at the terminal reaches of a Martian outflow channel. These generally appear highly resurfaced, or buried, at other locations in the planet. Rodriguez and his co-authors propose in an article titled "Infiltration of Martian overflow channel floodwaters into lowland cavernous systems" published in Geophysical Research Letters that large volumes of catastrophic floodwaters, which participated in the excavation of Hebrus Valles, may have encountered their ultimate fate in vast cavernous systems.

They hypothesize that evacuated subsurface space during mud volcanism was an important process in cavern development. Mud volcanism can expel vast volumes of subsurface volatiles and sediments to the surface. But because evacuation of subsurface materials generally occurs within unconsolidated sediments resulting caverns are transient and mechanically highly unstable.

However, the investigated Martian caverns appear to have developed within permafrost, which at -65 degrees Celsius (-85 degree Fahrenheit) - a typical mean annual surface temperature for the investigated latitudes - has a mechanical strength similar to that of limestone. Limestone rocks host most of the terrestrial cavern systems.

Researchers have discovered what may be the earliest dinosaur, a creature the size of a Labrador retriever, but with a five foot-long tail, that walked the Earth about 10 million years before more familiar dinosaurs like the small, swift-footed Eoraptor and Herrerasaurus.

The findings mean that the dinosaur lineage appeared 10 million to 15 million years earlier than fossils previously showed, originating in the Middle Triassic rather than in the Late Triassic period.

"If the newly named Nyasasaurus parringtoni is not the earliest dinosaur, then it is the closest relative found so far," according to Sterling Nesbitt, a University of Washington postdoctoral researcher in biology and lead author of a paper published online Dec. 5 in Biology Letters, a journal of the United Kingdom's Royal Society.

"For 150 years, people have been suggesting that there should be Middle Triassic dinosaurs, but all the evidence is ambiguous," he said. "Some scientists used fossilized footprints, but we now know that other animals from that time have a very similar foot. Other scientists pointed to a single dinosaur-like characteristic in a single bone, but that can be misleading because some characteristics evolved in a number of reptile groups and are not a result of a shared ancestry."

The researchers had one humerus – or upper arm bone – and six vertebrae to work with. They determined that the animal likely stood upright, measured 7 to 10 feet in length (2 to 3 meters), was as tall as 3 feet at the hip (1 meter) and may have weighed between 45 and 135 pounds (20 to 60 kilograms).

The fossilized bones were collected in the 1930s from Tanzania, but it may not be correct to say dinosaurs originated in that country. When Nyasasaurus parringtoni lived, the world's continents were joined in the landmass called Pangaea. Tanzania would have been part of Southern Pangaea that included Africa, South America, Antarctica and Australia.

"The new findings place the early evolution of dinosaurs and dinosaur-like reptiles firmly in the southern continents," said co-author Paul Barrett at the Natural History Museum, London.

The bones of the new animal reveal a number of characteristics common to early dinosaurs and their close relatives. For example, the bone tissues in the upper arm bone appear as if they are woven haphazardly and not laid down in an organized way. This indicates rapid growth, a common feature of dinosaurs and their close relatives.

"We can tell from the bone tissues that Nyasasaurus had a lot of bone cells and blood vessels," said co-author Sarah Werning at the University of California, Berkeley, who did the bone analysis. "In living animals, we only see this many bone cells and blood vessels in animals that grow quickly, like some mammals or birds."

"The bone tissue of Nyasasaurus is exactly what we would expect for an animal at this position on the dinosaur family tree," she added. "It's a very good example of a transitional fossil; the bone tissue shows that Nyasasaurus grew about as fast as other primitive dinosaurs, but not as fast as later ones."

Another example is the upper arm bone's distinctively enlarged crest, needed to anchor the upper arm muscles. The feature, known as an elongated deltopectoral crest, is also common to all early dinosaurs.

"Nyasasaurus and its age have important implications regardless of whether this taxon is a dinosaur or the closest relatives of dinosaurs," Nesbitt said. "It establishes that dinosaurs likely evolved earlier than previously expected and refutes the idea that dinosaur diversity burst onto the scene in the Late Triassic, a burst of diversification unseen in any other groups at that time."

It now appears that dinosaurs were just part of a large diversification of archosaurs. Archosaurs were among the dominant land animals during the Triassic period 250 million to 200 million years ago and include dinosaurs, crocodiles and their kin.

"Dinosaurs are just part of this archosaur diversification, an explosion of new forms soon after the Permian extinction," Nesbitt said.